The Study on Characteristics of Dissimilar Weld Metals between AA6061-T6 and Silafont-36 by Laser Welding

Abstract

The characteristics of dissimilar weld metals between AA6061-T6 and Silafont-36 by laser welding were evaluated in terms of bead shape, microstructure, EDS analysis, hardness, and tensile strength. Laser power of 3.0, 3.5, 4.0kW and incident angle of 15, 20° were employed to make dissimilar weld metals. Bead shape of weld metal with 3.5kW, 15° was most stable. Microstructure of dissimilar weld metals consisted of columnar dendrite in area adjacent to fusion line and equiaxed dendrite in center of weld metal. Also, Mg2Si and α-AlFeMnSi were precipitated in weld metal. Microstructure in HAZ of Silafont-36 consisted of eutectic Al-Si, Mg2Si, and β-Al5FeSi. Si contents of weld metal made with 4.0kW, 15° were very high. And Mg contents of weld metals were relatively low because of vaporation of Mg. Hardness of weld metal made with 4.0kW, 15° was very high because Si contents of that were high. In tensile test, Specimens were fractured in Silafont-36 or weld metals. The fracture in base metals was due to low tensile strength of Silafont-36, and the fracture in weld metals was due to undercut or porosity. Key words: AA6061, Silafont-36, Dissimilar weld, Laser welding, Mg2Si